Acceleration without gravity

I'm [trying] to measure hand speed when you throw disk or ball,

If I am throwing a frisbee, the actual throw probably takes place over a quarter second or less. The acceleration due to the throw could be multiple orders of magnitude greater than gravity.

I have heard quotes that a frisbee throw can involve instantaneous force vectors of 150 times the force of gravity. If you just ignore any data point where the accelerometer is reading a vector with a magnitude less than 10 Gs, and then don't even bother to account for gravity, you will probably be able to end up with less than 5-10% error overall compared to if you did account for gravity (which also might not be perfectly accurate, but that's a different problem).

https://www.youtube.com/watch?v=x4wnbKYfPLs

On top of that, if you have a magnitude limit, you can throw for 30 minutes and end up with only like 10 seconds of actual data that you need to save.